package com.artlongs.framework.query;

/**
 * Created by ${leeton} on 2018/7/27.
 */

import java.util.Comparator;
import java.util.Iterator;
import java.util.Optional;
import java.util.Spliterator;
import java.util.function.*;
import java.util.stream.*;

public abstract class LazyWrappedStream<T> implements Stream<T>{

    Stream<T> wrappedStream;

    protected LazyWrappedStream() {}
    protected LazyWrappedStream(QA<T> wrappedStream)
    {
        this.wrappedStream = wrappedStream;
    }

    protected void realizeStream()
    {
        // TODO: Perhaps this should only be called when the data from the
        // stream is actually used and not when the stream is being set-up.
        if (wrappedStream == null) wrappedStream = createWrappedStream();
    }


    /**
     * Allows subclasses to wrap streams generated by this class
     * with wrappers that provide additional functionality.
     */
    protected <U> Stream<U> wrap(Stream<U> toWrap)
    {
        return toWrap;
    }

    protected QA<T> createWrappedStream()
    {
        return null;
    }

    @Override
    public Stream<T> filter(Predicate<? super T> predicate)
    {
        realizeStream();
        return wrap(wrappedStream.filter(predicate));
    }

    @Override
    public <R> Stream<R> map(Function<? super T, ? extends R> mapper) {
        realizeStream();
        return wrappedStream.map(mapper);
    }

    @Override
    public IntStream mapToInt(ToIntFunction<? super T> mapper)
    {
        realizeStream();
        return wrappedStream.mapToInt(mapper);
    }

    @Override
    public LongStream mapToLong(ToLongFunction<? super T> mapper)
    {
        realizeStream();
        return wrappedStream.mapToLong(mapper);
    }

    @Override
    public DoubleStream mapToDouble(ToDoubleFunction<? super T> mapper)
    {
        realizeStream();
        return wrappedStream.mapToDouble(mapper);
    }

    @Override
    public <R> Stream<R> flatMap(
            Function<? super T, ? extends Stream<? extends R>> mapper)
    {
        realizeStream();
        return wrap(wrappedStream.flatMap(mapper));
    }

    @Override
    public IntStream flatMapToInt(Function<? super T, ? extends IntStream> mapper)
    {
        realizeStream();
        return wrappedStream.flatMapToInt(mapper);
    }

    @Override
    public LongStream flatMapToLong(
            Function<? super T, ? extends LongStream> mapper)
    {
        realizeStream();
        return wrappedStream.flatMapToLong(mapper);
    }

    @Override
    public DoubleStream flatMapToDouble(
            Function<? super T, ? extends DoubleStream> mapper)
    {
        realizeStream();
        return wrappedStream.flatMapToDouble(mapper);
    }

    @Override
    public Stream<T> distinct()
    {
        realizeStream();
        return wrap(wrappedStream.distinct());
    }

    @Override
    public Stream<T> sorted()
    {
        realizeStream();
        return wrap(wrappedStream.sorted());
    }

    @Override
    public Stream<T> sorted(Comparator<? super T> comparator)
    {
        realizeStream();
        return wrap(wrappedStream.sorted(comparator));
    }

    @Override
    public Stream<T> peek(Consumer<? super T> action)
    {
        realizeStream();
        return wrap(wrappedStream.peek(action));
    }

    @Override
    public Stream<T> limit(long maxSize)
    {
        realizeStream();
        return wrap(wrappedStream.limit(maxSize));
    }

    @Override
    public Stream<T> skip(long n)
    {
        realizeStream();
        return wrap(wrappedStream.skip(n));
    }

    @Override
    public void forEach(Consumer<? super T> action)
    {
        realizeStream();
        wrappedStream.forEach(action);
    }

    @Override
    public void forEachOrdered(Consumer<? super T> action)
    {
        realizeStream();
        wrappedStream.forEachOrdered(action);
    }

    @Override
    public Object[] toArray()
    {
        realizeStream();
        return wrappedStream.toArray();
    }

    @Override
    public <A> A[] toArray(IntFunction<A[]> generator)
    {
        realizeStream();
        return wrappedStream.toArray(generator);
    }

    @Override
    public T reduce(T identity, BinaryOperator<T> accumulator)
    {
        realizeStream();
        return wrappedStream.reduce(identity, accumulator);
    }

    @Override
    public Optional<T> reduce(BinaryOperator<T> accumulator)
    {
        realizeStream();
        return wrappedStream.reduce(accumulator);
    }

    @Override
    public <U> U reduce(U identity, BiFunction<U, ? super T, U> accumulator,
                        BinaryOperator<U> combiner)
    {
        realizeStream();
        return wrappedStream.reduce(identity, accumulator, combiner);
    }

    @Override
    public <R> R collect(Supplier<R> supplier,
                         BiConsumer<R, ? super T> accumulator, BiConsumer<R, R> combiner)
    {
        realizeStream();
        return wrappedStream.collect(supplier, accumulator, combiner);
    }

    @Override
    public <R, A> R collect(Collector<? super T, A, R> collector)
    {
        realizeStream();
        return wrappedStream.collect(collector);
    }

    @Override
    public Optional<T> min(Comparator<? super T> comparator)
    {
        realizeStream();
        return wrappedStream.min(comparator);
    }

    @Override
    public Optional<T> max(Comparator<? super T> comparator)
    {
        realizeStream();
        return wrappedStream.max(comparator);
    }

    @Override
    public long count()
    {
        realizeStream();
        return wrappedStream.count();
    }

    @Override
    public boolean anyMatch(Predicate<? super T> predicate)
    {
        realizeStream();
        return wrappedStream.anyMatch(predicate);
    }

    @Override
    public boolean allMatch(Predicate<? super T> predicate)
    {
        realizeStream();
        return wrappedStream.allMatch(predicate);
    }

    @Override
    public boolean noneMatch(Predicate<? super T> predicate)
    {
        realizeStream();
        return wrappedStream.noneMatch(predicate);
    }

    @Override
    public Optional<T> findFirst()
    {
        realizeStream();
        return wrappedStream.findFirst();
    }

    @Override
    public Optional<T> findAny()
    {
        realizeStream();
        return wrappedStream.findAny();
    }

    @Override
    public Iterator<T> iterator()
    {
        realizeStream();
        return wrappedStream.iterator();
    }

    @Override
    public Spliterator<T> spliterator()
    {
        realizeStream();
        return wrappedStream.spliterator();
    }

    @Override
    public boolean isParallel()
    {
        realizeStream();
        return wrappedStream.isParallel();
    }

    @Override
    public Stream<T> sequential()
    {
        realizeStream();
        return wrap(wrappedStream.sequential());
    }

    @Override
    public Stream<T> parallel()
    {
        realizeStream();
        return wrap(wrappedStream.parallel());
    }

    @Override
    public Stream<T> unordered()
    {
        realizeStream();
        return wrap(wrappedStream.unordered());
    }

    @Override
    public Stream<T> onClose(Runnable closeHandler)
    {
        realizeStream();
        return wrap(wrappedStream.onClose(closeHandler));
    }

    @Override
    public void close()
    {
        realizeStream();
        wrappedStream.close();
    }
}
